Chiral beta-hydroxyethylamines and their use in the treatment of hyperglycemia

ABSTRACT

There is herein provided a compound of formula (I) or a pharmaceutically acceptable salt thereof, wherein X, R1, R2, R3, R4 and n have meanings as provided in the description.

FIELD OF THE INVENTION

The present invention relates to novel compounds and compositions, and their use in the treatment of hyperglycaemia and disorders characterised by hyperglycaemia, such as type 2 diabetes. In particular, the invention relates to novel compounds, compositions and methods for the treatment of conditions such as type 2 diabetes through activation of the β₂-adrenergic receptor. Importantly, such compounds are thought to have a beneficial side-effect profile as they do not exert their effect through significant cAMP release.

BACKGROUND OF THE INVENTION

The listing or discussion of an apparently prior-published document in this specification should not necessarily be taken as an acknowledgement that the document is part of the state of the art or is common general knowledge.

Hyperglycaemia, or high blood sugar is a condition in which an excessive amount of glucose circulates in the blood plasma. If not treated, hyperglycaemia can be a serious problem, potentially developing into life-threatening conditions such as ketoacidosis. For example, chronic hyperglycemia may cause injury to the heart, and is strongly associated with heart attacks and death in subjects with no coronary heart disease or history of heart failure. There are various causes of hyperglycaemia, including diabetes and severe insulin resistance.

Severe insulin resistance (SIR) is a condition wherein the patient experiences very low levels of (or, in extreme cases, no significant) response to insulin. There are several syndromes characterized by SIR, including Rabson-Mendenhall syndrome, Donohue's syndrome (leprechaunism), Type A and Type B syndromes of insulin resistance, the HAIR-AN (hyperandrogenism, insulin resistance, and acanthosis nigricans) syndrome, pseudoacromegaly, and lipodystrophy. The majority of these conditions have genetic causes, such as mutations in the insulin receptor gene. The prevalence for Donohue's syndrome, Rabson-Mendenhall syndrome and Type A syndrome of insulin resistance, has been reported to vary from about 50 reported cases to 1 in 100,000. However, since some diseases are severe and extremely rare, it is likely that many patients do not get diagnosed before they die, particularly in less developed areas of the world. Thus, the exact number of patients with these syndromes is difficult to assess.

The current standard for hyperglycaemia treatment in patients having SIR is a controlled diet, supplemented with drugs affecting insulin receptor sensitivity, such as metformin, or insulin supplement. However, particularly for disorders caused by mutations in the insulin receptor gene, this treatment is not sufficiently effective and ultimately proves unsuccessful.

Diabetes comprises two distinct diseases, type 1 (or insulin-dependent diabetes) and type 2 (insulin-independent diabetes), both of which involve the malfunction of glucose homeostasis. Type 2 diabetes affects more than 400 million people in the world and the number is rising rapidly. Complications of type 2 diabetes include severe cardiovascular problems, kidney failure, peripheral neuropathy, blindness and, in the later stages of the disease, even loss of limbs and, ultimately death. Type 2 diabetes is characterized by insulin resistance in skeletal muscle and adipose tissue, and there is presently no definitive cure. Most treatments used today are focused on remedying dysfunctional insulin signalling or inhibiting glucose output from the liver but many of those treatments have several drawbacks and side effects. There is thus a great interest in identifying novel insulin-independent ways to treat type 2 diabetes.

In type 2 diabetes, the insulin-signalling pathway is blunted in peripheral tissues such as adipose tissue and skeletal muscle. Methods for treating type 2 diabetes typically include lifestyle changes, as well as insulin injections or oral medications to regulate glucose homeostasis. People with type 2 diabetes in the later stages of the disease develop ‘beta-cell failure’ i.e. the inability of the pancreas to release insulin in response to high blood glucose levels. In the later stages of the disease patients often require insulin injections in combination with oral medications to manage their diabetes. Further, most common drugs have side effects including downregulation or desensitization of the insulin pathway and/or the promotion of lipid incorporation in adipose tissue, liver and skeletal muscle. There is thus a great interest in identifying novel ways to treat metabolic diseases including type 2 diabetes that do not include these side effects.

Following a meal, increased blood glucose levels stimulate insulin release from the pancreas. Insulin mediates normalization of the blood glucose levels. Important effects of insulin on glucose metabolism include facilitation of glucose uptake into skeletal muscle and adipocytes, and an increase of glycogen storage in the liver. Skeletal muscle and adipocytes are responsible for insulin-mediated glucose uptake and utilization in the fed state, making them very important sites for glucose metabolism.

The signalling pathway downstream from the insulin receptor has been difficult to understand in detail. In brief, control of glucose uptake by insulin involves activation of the insulin receptor (IR), the insulin receptor substrate (IRS), the phosphoinositide 3-kinase (PI3K) and thus stimulation of phosphatidylinositol (3,4,5)-triphosphate (PIP3), the mammalian target of rapamycin (also called the mechanistic target of rapamycin, mTOR), Akt/PKB (Akt) and TBC1D4 (AS160), leading to translocation of the glucose transporter 4 (GLUT4) to the plasma membrane. Akt activation is considered necessary for GLUT4 translocation.

It should be noted that skeletal muscles constitute a major part of the body weight of mammals and have a vital role in the regulation of systemic glucose metabolism, being responsible for up to 85% of whole-body glucose disposal. Glucose uptake in skeletal muscles is regulated by several intra- and extracellular signals. Insulin is the most well studied mediator but others also exist. For example, AMP activated kinase (AMPK) functions as an energy sensor in the cell, which can increase glucose uptake and fatty acid oxidation. Due to the great influence skeletal muscles have on glucose homeostasis it is plausible that additional mechanisms exist. In the light of the increased prevalence of type 2 diabetes, it is of great interest to find and characterize novel insulin-independent mechanisms to increase glucose uptake in muscle cells.

Blood glucose levels may be regulated by both insulin and catecholamines, but they are released in the body in response to different stimuli. Whereas insulin is released in response to the rise in blood sugar levels (e.g. after a meal), epinephrine and norepinephrine are released in response to various internal and external stimuli, such as exercise, emotions and stress, and also for maintaining tissue homeostasis. Insulin is an anabolic hormone that stimulates many processes involved in growth including glucose uptake, glycogen and triglyceride formation, whereas catecholamines are mainly catabolic.

Although insulin and catecholamines normally have opposing effects, it has been shown that they have similar actions on glucose uptake in skeletal muscle (Nevzorova et al., Br. J. Pharmacol, 137, 9, (2002)). In particular, it has been reported that catecholamines stimulate glucose uptake via adrenergic receptors (Nevzorova et al., Br. J. Pharmacol, 147, 446, (2006); Hutchinson, Bengtsson Endocrinology 146, 901, (2005)) to supply muscle cells with an energy-rich substrate. Thus it is likely that in mammals, including humans, the adrenergic and the insulin systems can work independently to regulate the energy needs of skeletal muscle in different situations. Since insulin also stimulates many anabolic processes, including some that promote undesired effects such as stimulation of lipid incorporation into tissues, leading to e.g. obesity, it would be beneficial to be able to stimulate glucose uptake by other means; for example, by stimulation of the adrenergic receptors (ARs).

All ARs are G protein-coupled receptors (GPCRs) located in the cell membrane and characterized by an extracellular N-terminus, followed by seven transmembrane α-helices (TM-1 to TM-7) connected by three intracellular (IL-1 to IL-3) and three extracellular loops (EL-1 to EL-3), and finally an intracellular C-terminus. There are three different classes of ARs, with distinct expression patterns and pharmacological profiles: α₁-, α₂- and β-ARs. The α₁-ARs comprise the α_(1A), α_(1B) and α_(1D) subtypes while α₂-ARs are divided into α_(2A), α_(2B) and α₂c. The β-ARs are also divided into the subtypes β₁, β₂, and β₃, of which β₂-AR is the major isoform in skeletal muscle cells. ARs are G protein coupled receptors (GPCRs) that signal through classical secondary messengers such as cyclic adenosine monophosphate (cAMP) and phospholipase C (PLC).

Many effects occurring downstream of ARs in skeletal muscles have been attributed to classical secondary messenger signalling, such as increase in cAMP levels, PLC activity and calcium levels. Stimulation involving the classical secondary messengers has many effects in different tissues. For example, it increases heart rate, blood flow, airflow in lungs and release of glucose from the liver, which all can be detrimental or be considered unwanted side effects if stimulation of ARs should be considered as a type 2 diabetes treatment. Adverse effects of classical AR agonists are, for example, tachycardia, palpitation, tremor, sweats, agitation and increased glucose levels in the blood (glucose output from the liver). It would thus be beneficial to be able to activate ARs without activating these classical secondary messengers, such as cAMP, to increase glucose uptake in peripheral tissues without stimulating the unwanted side effects.

Glucose uptake is mainly stimulated via facilitative glucose transporters (GLUT) that mediate glucose uptake into most cells. GLUTs are transporter proteins that mediate transport of glucose and/or fructose over the plasma membrane down the concentration gradient. There are fourteen known members of the GLUT family, named GLUT1-14, divided into three classes (Class I, Class II and Class III) dependent on their substrate specificity and tissue expression. GLUT1 and GLUT4 are the most intensively studied isoforms and, together with GLUT2 and GLUT3, belong to Class I which mainly transports glucose (in contrast to Class II that also transports fructose). GLUT1 is ubiquitously expressed and is responsible for basal glucose transport. GLUT4 is only expressed in peripheral tissues such as skeletal muscle, cardiac muscle and adipose tissues. GLUT4 has also been reported to be expressed in, for example, the brain, kidney, and liver. GLUT4 is the major isoform involved in insulin stimulated glucose uptake. The mechanism whereby insulin signalling increases glucose uptake is mainly via GLUT4 translocation from intracellular storage to the plasma membrane. It is known that GLUT4 translocation is induced by stimulation of the β₂-adrenergic receptor.

Thus, a possible treatment of a condition involving dysregulation of glucose homeostasis or glucose uptake in a mammal, such as type 2 diabetes, would involve the activation of the β₂-adrenergic receptor leading to GLUT4 translocation to the plasma membrane and promotion of glucose uptake into skeletal muscle leading to normalization of whole body glucose homeostasis. In addition, it would be advantageous if the treatment does not involve signalling through cAMP as this would lead to a favourable side-effect profile.

The vasodilator 4-(2-(butylamino)-1-hydroxyethyl)phenol, which has been used in the treatment of peripheral vascular disorders, has been found to initially increase blood sugar and has been contraindicated in diabetes and pre-diabetes (see Unger, H., Zeitschrift für die Gesamte Innere Medizin und Ihre Grenzgebiete, 16, 742 (1961)).

DESCRIPTION OF THE INVENTION

We have now surprisingly found that certain chiral β-hydroxyethylamines acting as agonists at the β₂-adrenergic receptor increase glucose uptake in skeletal muscle.

In addition, we have found that this effect is not mediated through significant cAMP release, such that many of the commonly described side effects seen with traditional β₂-adrenergic agonists (e.g. tachycardia, palpitation, tremor, sweats, agitation, and the like) can be reduced.

The use of such compounds in medicine represents a promising strategy for the treatment of conditions characterized by high blood sugar levels (i.e. hyperglycaemia), such as type 2 diabetes.

Compounds of the Invention

In a first aspect of the invention, there is provided a compound of formula I

or a pharmaceutically acceptable salt thereof, wherein:

R¹ represents C₃₋₁₁ alkyl optionally substituted by one or more halo;

R² represents C₁₋₂ alkyl optionally substituted by one or more halo;

R³ and R⁴ each independently represent H or C₁₋₃ alkyl optionally substituted by one or more halo;

or R³ and R⁴ may be linked together to form, together with the carbon atom to which they are attached, a 3- to 6-membered ring, which ring optionally is substituted by one or more groups independently selected from halo and C₁ alkyl optionally substituted by one or more halo;

each X independently represents halo, R^(a), —CN, —N₃, —N(R^(b))R^(c), —NO₂, —ONO₂, —OR^(d), —S(O)_(p)R^(e) or —S(O)_(q)N(R^(f))R^(g);

R^(a) represents C₁₋₆ alkyl optionally substituted by one or more groups independently selected from G;

each R^(b), R^(c), R^(d), R^(e), R^(f) and R^(g) independently represents H or C₁₋₆ alkyl optionally substituted by one or more groups independently selected from G;

or alternatively any of R^(b) and R^(c) and/or R^(f) and R^(g) may be linked together to form, together with the nitrogen atom to which they are attached, a 4- to 6-membered ring, which ring optionally contains one further heteroatom and which ring optionally is substituted by one or more groups independently selected from halo, C₁₋₃ alkyl optionally substituted by one or more halo, and ═O;

G represents halo, —CN, —N(R^(a1))R^(b1), —OR^(c1), —S(O)_(p)R^(d1), —S(O)_(q)N(R^(e1))R^(f1) or ═O;

each R^(a1), R^(b1), R^(c1), R^(d1), R^(e1) and R^(f1) independently represents H or C₁₋₆ alkyl optionally substituted by one or more halo;

or alternatively any of R^(a1) and R^(b1) and/or R^(e1) and R^(f1) may be linked together to form, together with the nitrogen atom to which they are attached, a 4- to 6-membered ring, which ring optionally contains one further heteroatom and which ring optionally is substituted by one or more groups independently selected from halo, C₁₋₃ alkyl optionally substituted by one or more halo, and ═O;

n represents 0 to 5;

each p independently represents 0, 1 or 2; and

each q independently represents 1 or 2,

which compounds (including pharmaceutically acceptable salts) may be referred to herein as the “compounds of the invention”.

For the avoidance of doubt, the skilled person will understand that references herein to compounds of particular aspects of the invention (such as the first aspect of the invention, e.g. compounds of formula I) will include references to all embodiments and particular features thereof, which embodiments and particular features may be taken in combination to form further embodiments.

Unless indicated otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

Pharmaceutically acceptable salts include acid addition salts and base addition salts. Such salts may be formed by conventional means, for example by reaction of a free acid or a free base form of a compound of the invention with one or more equivalents of an appropriate acid or base, optionally in a solvent, or in a medium in which the salt is insoluble, followed by removal of said solvent, or said medium, using standard techniques (e.g. in vacuo, by freeze-drying or by filtration). Salts may also be prepared by exchanging a counter-ion of a compound of the invention in the form of a salt with another counter-ion, for example using a suitable ion exchange resin.

Particular acid addition salts that may be mentioned include carboxylate salts (e.g. formate, acetate, trifluoroacetate, propionate, isobutyrate, heptanoate, decanoate, caprate, caprylate, stearate, acrylate, caproate, propiolate, ascorbate, citrate, glucuronate, glutamate, glycolate, α-hydroxybutyrate, lactate, tartrate, phenylacetate, mandelate, phenylpropionate, phenylbutyrate, benzoate, chlorobenzoate, methylbenzoate, hydroxybenzoate, methoxybenzoate, dinitrobenzoate, o-acetoxy-benzoate, salicylate, nicotinate, isonicotinate, cinnamate, oxalate, malonate, succinate, suberate, sebacate, fumarate, malate, maleate, hydroxymaleate, hippurate, phthalate or terephthalate salts), halide salts (e.g. chloride, bromide or iodide salts), sulphonate salts (e.g. benzenesulphonate, methyl-, bromo- or chloro-benzenesulphonate, xylenesulphonate, methanesulphonate, ethanesulphonate, propanesulphonate, hydroxy-ethanesulphonate, 1- or 2-naphthalene-sulphonate or 1,5-naphthalenedisulphonate salts) or sulphate, pyrosulphate, bisulphate, sulphite, bisulphite, phosphate, monohydrogenphosphate, dihydrogenphosphate, metaphosphate, pyrophosphate or nitrate salts, and the like.

Particular base addition salts that may be mentioned include salts formed with alkali metals (such as Na and K salts), alkaline earth metals (such as Mg and Ca salts), organic bases (such as ethanolamine, diethanolamine, triethanolamine, tromethamine and lysine) and inorganic bases (such as ammonia and aluminium hydroxide). More particularly, base addition salts that may be mentioned include Mg, Ca and, most particularly, K and Na salts.

For the avoidance of doubt, compounds of the first aspect of the invention may exist as solids, and thus the scope of the invention includes all amorphous, crystalline and part crystalline forms thereof, and may also exist as oils. Where compounds of the first aspect of the invention exist in crystalline and part crystalline forms, such forms may include solvates, which are included in the scope of the invention. Compounds of the first aspect of the invention may also exist in solution.

Compounds of the first aspect of the invention may contain double bonds and may thus exist as E (entgegen) and Z (zusammen) geometric isomers about each individual double bond. All such isomers and mixtures thereof are included within the scope of the invention.

Compounds of the first aspect of the invention may also exhibit tautomerism. All tautomeric forms and mixtures thereof are included within the scope of the invention.

Compounds of the first aspect of the invention also contain more than one or asymmetric carbon atoms and may therefore exhibit optical and/or diastereoisomerism. Diastereoisomers may be separated using conventional techniques, e.g. chromatography or fractional crystallisation. The various stereoisomers (i.e. enantiomers) may be isolated by separation of a racemic or other mixture of the compounds using conventional, e.g. fractional crystallisation or HPLC, techniques. Alternatively the desired optical isomers may be obtained from appropriate optically active starting materials under conditions which will not cause racemisation or epimerisation (i.e. a ‘chiral pool’ method), by reaction of the appropriate starting material with a ‘chiral auxiliary’ which can subsequently be removed at a suitable stage, by derivatisation (i.e. a resolution, including a dynamic resolution); for example, with a homochiral acid followed by separation of the diastereomeric derivatives by conventional means such as chromatography, or by reaction with an appropriate chiral reagent or chiral catalyst all under conditions known to the skilled person. All stereoisomers and mixtures thereof are included within the scope of the invention.

As used herein, references to halo and/or halogen groups will each independently refer to fluoro, chloro, bromo and iodo (for example, fluoro (F) and chloro (Cl), such as F).

Unless otherwise specified, C_(1-z) alkyl groups (where z is the upper limit of the range) defined herein may be straight-chain or, when there is a sufficient number (i.e. a minimum of three) of carbon atoms, be branched-chain, and/or cyclic (so forming a C_(3-z)-cycloalkyl group). When there is a sufficient number (i.e. a minimum of four) of carbon atoms, such groups may also be part cyclic. Part cyclic alkyl groups that may be mentioned include cyclopropylmethyl and cyclohexylethyl. When there is a sufficient number of carbon atoms, such groups may also be multicyclic (e.g. bicyclic or tricyclic) or spirocyclic. Such alkyl groups may also be saturated or, when there is a sufficient number (i.e. a minimum of two) of carbon atoms, be unsaturated (forming, for example, a C_(2-z) alkenyl or a C_(2-z) alkynyl group). Particular alkyl groups that may be mentioned include saturated alkyl groups.

For the avoidance of doubt, as used herein, references to heteroatoms will take their normal meaning as understood by one skilled in the art. Particular heteroatoms that may be mentioned include phosphorus, selenium, tellurium, silicon, boron, oxygen, nitrogen and sulphur (e.g. oxygen, nitrogen and sulphur).

For the avoidance of doubt, references to polycyclic (e.g. bicyclic or tricyclic) groups (e.g. when employed in the context of cycloalkyl groups) will refer to ring systems wherein at least two scissions would be required to convert such rings into a straight chain, with the minimum number of such scissions corresponding to the number of rings defined (e.g. the term bicyclic may indicate that a minimum of two scissions would be required to convert the rings into a straight chain). For the avoidance of doubt, the term bicyclic (e.g. when employed in the context of alkyl groups) may refer to groups in which the second ring of a two-ring system is formed between two adjacent atoms of the first ring, and may also refer to groups in which two non-adjacent atoms are linked by an alkylene group, which later groups may be referred to as bridged.

The present invention also embraces isotopically-labelled compounds of the present invention which are identical to those recited herein, but for the fact that one or more atoms are replaced by an atom having an atomic mass or mass number different from the atomic mass or mass number usually found in nature (or the most abundant one found in nature). All isotopes of any particular atom or element as specified herein are contemplated within the scope of the compounds of the invention. Hence, the compounds of the invention also include deuterated compounds, i.e. in which one or more hydrogen atoms are replaced by the hydrogen isotope deuterium.

For the avoidance of doubt, in cases in which the identity of two or more substituents in a compound of the invention may be the same, the actual identities of the respective substituents are not in any way interdependent. For example, in the situation in which two or more X groups are present, those X groups may be the same or different. Similarly, where two or more X groups are present and each represent halo, the halo groups in question may be the same or different. Likewise, when more than one R^(a) is present and each independently represents C₁₋₆ alkyl substituted by one or more G group, the identities of each G are in no way interdependent.

The skilled person will appreciate that compounds of the invention that are the subject of this invention include those that are stable. That is, compounds of the invention include those that are sufficiently robust to survive isolation, e.g. from a reaction mixture, to a useful degree of purity.

All embodiments of the invention and particular features mentioned herein may be taken in isolation or in combination with any other embodiments and/or particular features mentioned herein (hence describing more particular embodiments and particular features as disclosed herein) without departing from the disclosure of the invention.

For the avoidance of doubt, it is provided that R¹ comprises a greater number of carbon atoms than R². Thus, where R² represents C₁₋₂ alkyl, R¹ will represent C₃₋₁₁ alkyl.

In certain embodiments of the first aspect of the invention, R¹ represents C₃₋₉ alkyl optionally substituted by one or more F.

In certain embodiments of the first aspect of the invention, R¹ represents C₃₋₆ alkyl optionally substituted by one or more F.

Particular R¹ groups which may be mentioned include n-propyl, isopropyl, n-butyl, sec-butyl, —CH₂-cyclopropyl, 2-pentyl, cyclopentyl, n-hexyl and cyclohexyl. In particular embodiments of the invention, R¹ represents n-propyl.

In other embodiments of the first aspect of the invention, R² represents C₁₋₂ alkyl optionally substituted by one or more F. In particular embodiments, R² represents methyl.

In particular embodiments of the first aspect of the invention, there is provided a compound of the invention wherein R¹ represents n-propyl or n-butyl, and R² represents methyl. In yet more particular embodiments, there is provided a compound of the invention wherein R¹ represents n-propyl and R² represents methyl.

The skilled person will understand that the prefixes “n-”, “sec-” and “tert-” when applied to alkyl groups indicate the terms “normal”, “secondary” and “tertiary”. The term “normal” indicates a linear alkyl group where the point of attachment of the group to the rest of a molecule is through a carbon atom at the end of the carbon chain and thus that that carbon atom is bound to one other carbon atom. The term “secondary” indicates that the point of attachment of the rest of the molecule to the alkyl group is through a carbon atom adjacent to the end of the carbon chain and thus that that carbon is itself bound to two other carbon atoms. The term “tertiary” indicates that the point of attachment of the alkyl group to the rest of a molecule is through a carbon atom that is bound to three other carbon atoms.

In particular embodiments of the first aspect of the invention, each R³ and R⁴ independently represents H or C₁₋₂ alkyl (e.g. methyl). In more particular embodiments, R³ and R⁴ each represent H.

In certain embodiments of the compounds of the invention, each X independently represents halo, R^(a), —CN, —N₃, —N(R^(b))R^(c), —NO₂ or —OR^(d), wherein R^(a) represents C₁₋₄ alkyl optionally substituted by one or more F, and wherein R^(b), R^(c) and R^(d) each independently represent H or C₁₋₄ alkyl optionally substituted by one or more F or ═O.

In further embodiments, each X may independently represent halo, R^(a), —CN, —N(R^(b))R^(c), or —OR^(d), wherein R^(a) represents C₁₋₄ alkyl optionally substituted by one or more F, and wherein R^(b), R^(c) and R^(d) each independently represent H or C₁₋₄ alkyl optionally substituted by one or more F.

In particular embodiments that may be mentioned, R^(d) represents H.

In more particular embodiments, each X independently represents F, Cl, R^(a), —NH₂ or —OH, wherein R^(a) represents C₁₋₄ alkyl (e.g. C₁₋₂ alkyl) optionally substituted by one or more F (for example R^(a) represents —CHF₂ or —CF₃ (e.g. —CF₃)).

In yet more particular embodiments, each X independently represents F, —CF₃, —NH₂, or —OH. In yet further embodiments, each X independently represents F or —OH (e.g. F).

In certain embodiments, each X independently represents Cl, F, —CF₃, —NH₂, or —OH. In further embodiments, each X independently represents Cl, F or —OH (e.g. Cl or F), particularly where n represents 0 to 2 (e.g. 1 or 2, such as 1).

In particular embodiments of the compounds of the invention, n represents 0, 1, 2 or 3 (for example 1 or 2, e.g. 1).

In certain embodiments of the compounds of the invention, n represents 0, 1 or 2 (e.g. 0 or 1).

In other embodiments of the compounds of the invention, n represents 1, 2 or 3 (e.g. 1 or 2).

In particular embodiments of the compounds of the invention, n represents 1.

In certain embodiments, when n represents 1 to 3, each X independently represents F or —OH and are located in the 3-, 4- and 5-positions.

In certain embodiments, when n represents 1 to 2, each X independently represents F or —OH (e.g. F) and are located in the 3- and 4-positions, or the 3- and 5-positions.

In further embodiments, there is provided a compound of formula I, or a pharmaceutically acceptable salt thereof, wherein the essential benzene ring is unsubstituted in the 2-, 5- and 6-positions.

In certain embodiments that may be mentioned, when n represents 2 or more (i.e. more than one X substituent is present), no more than one X may represent a group selected from —N(R^(b))R^(c) and —OR^(d) (particularly where R^(b), R^(c) and R^(d) represent H).

In particular embodiments:

each X independently represents H, F or —OH;

n represents 1 or 2 (e.g. 1); and/or (e.g. and)

at least one (e.g. one) X is in the 3- or in the 4-position on the phenyl group to which it is attached.

Particular embodiments of compounds of the invention include those wherein n represents 1 and X represents F or —OH.

Other particular embodiments of compounds of the invention include those wherein n represents 1 and X is located in the 3- or the 4-position.

Examples of particular embodiments include those wherein:

X represents F or —OH (e.g. —OH) in the 4-position on the phenyl group to which it is attached; and

n represents 1.

More examples of particular embodiments include those wherein:

X represents F or —OH (e.g. —OH) in the 3-position on the phenyl group to which it is attached; and

n represents 1.

For example, in a particular embodiment of the first aspect of the invention:

R¹ represents n-propyl;

R² represents methyl;

R³ and R³ represent H;

n represents 1; and

X represents F or —OH and is in the 4-position on the phenyl group to which it is attached.

In an alternative example, in a particular embodiment of the first aspect of the invention:

R¹ represents n-propyl;

R² represents methyl;

R³ and R³ represent H;

n represents 1; and

X represents F or —OH and is in the 3-position on the phenyl group to which it is attached.

For the avoidance of doubt, when R¹ represents n-propyl, R² represents methyl, R³ and R⁴ represent H, n represents 1 and X is —OH and is in the 4-position on the phenyl group to which it is attached, the compound of formula I may be depicted as:

In further particular embodiments of the compounds of the invention, the compound of formula I is a compound of formula IA

wherein R¹, R², R³ and R⁴ are as defined herein (for the avoidance of doubt, including all embodiments thereof), and X¹, X², X³, X⁴ and X⁵ each independently represent H or X, wherein X is as defined herein (for the avoidance of doubt, including all embodiments thereof).

In certain embodiments, there is provided a compound of formula IA, wherein:

X¹ and X⁵ each independently represent H; and

X², X³ and X⁴ each independently represent H, halo, R^(a), —CN, —N₃, —N(R^(b))R^(c), —NO₂ or —OR^(d), wherein R^(a) represents C₁₋₄ alkyl optionally substituted by one or more F, and wherein R^(b), R^(c) and R^(d) each independently represent H or C₁₋₄ alkyl optionally substituted by one or more F or ═O.

In particular embodiments, there is provided a compound of formula IA, wherein X² represents H.

In further embodiments, there is provided a compound of formula IA, wherein X³ or X⁴ each independently represent H, F, —NH₂ or —OH.

In particular embodiments, there is provided a compound of formula IA, wherein X³ or X⁴ each independently represents F or —OH.

In more particular embodiments, there is provided a compound of formula IA, wherein X³ represents F or —OH.

Thus, in further embodiments, there is provided a compound of formula IA, wherein:

X¹, X² and X⁵ each represent H; and

X³ and X⁴ each independently represent H, halo, R^(a), —CN, —NH₂, or —OH, wherein R^(a) represents C₁₋₂ alkyl optionally substituted by one or more F (for example R^(a) may represent —CH₃, —CF₃ or —CHF₂).

In more particular embodiments:

X¹, X² and X⁵ each represent H; and

X³ and X⁴ each independently represent H, halo, —NH₂, —CN or —OH.

In more particular embodiments:

X¹, X² and X⁵ each represent H; and

X³ and X⁴ each independently represent H, halo (e.g. F, Cl), —NH₂ or —OH.

In yet more particular embodiments:

X¹, X² and X⁵ each represent H; and

X³ and X⁴ each independently represent H, F or —OH.

Particular compounds of the first aspect of the invention that may be mentioned include the compounds of the examples provided herein, and pharmaceutically acceptable salts thereof. Thus, compounds of formula I that may be mentioned include:

-   4-(1-hydroxy-2-(((R)-pentan-2-yl)amino)ethyl) phenol -   3-(1-hydroxy-2-(((R)-pentan-2-yl)amino)ethyl) phenol -   1-(4-fluorophenyl)-2-(((R)-pentan-2-yl)amino)ethan-1-ol -   1-(3-fluorophenyl)-2-(((R)-pentan-2-yl)amino)ethan-1-ol

and pharmaceutically acceptable salts thereof.

As described herein, compounds of the first aspect of the invention may also contain one or more additional asymmetric carbon atoms and may therefore exhibit optical and/or diastereoisomerism. Moreover, it has been found that certain such optical and/or diastereoisomers may show increased utility in the treatment of hyperglycaemia or disorders characterized by hyperglycaemia (such as type 2 diabetes), as described herein.

In a particular embodiment of the first aspect of the invention, the compound of formula I is such that the carbon substituted with the essential —OH group is in the (R) configuration, as understood by those skilled in the art.

Thus, in a particular embodiment, the compound of formula I is a compound of formula IB

wherein n, X, R¹, R² and R³ are as described herein (i.e. as described in the first aspect of the invention, including all embodiments and particular features, and combinations thereof).

In particular embodiments, there is provided a compound of formula IB wherein:

n represents 1;

X represents F or —OH;

R¹ represents C₃₋₆ alkyl (e.g. C₃ alkyl, such as n-propyl);

R² represents C₁₋₂ alkyl (e.g. C₁ alkyl, such as methyl); and/or (e.g. and)

R² and R³ both represent H.

In more particular embodiments, there is provided a compound of formula IB wherein:

n represents 1;

X represents F or —OH and is in the 3- or 4-position of the phenyl group;

R¹ represents C₃₋₆ alkyl (e.g. C₃ alkyl, such as n-propyl);

R² represents C₁₋₂ alkyl (e.g. C₁ alkyl, such as methyl); and/or (e.g. and)

R² and R³ both represent H.

In a yet more particular embodiment, the compound of formula I (or the compound of formula IA or IB) is a compound of formula IC

wherein X¹, X², X³, X⁴, X⁵, R¹, R² and R³ are as described herein (i.e. as described in the first aspect of the invention, including all embodiments and particular features, and combinations thereof).

For example, there is provided a compound of formula IC wherein:

X¹, X² and X⁵ each represent H;

X³ and X⁴ each independently represent H, F or —OH;

R¹ represents C₃ alkyl;

R² represents C₁ alkyl; and

R³ and R⁴ both represent H.

As described herein, particular compounds of the first aspect of the invention that may be mentioned include the compounds of the examples provided herein, and pharmaceutically acceptable salts thereof. Thus, compounds of formula IB or IC that may be mentioned include:

-   4-((R)-1-hydroxy-2-(((R)-pentan-2-yl)amino)ethyl)phenol -   3-((R)-1-hydroxy-2-(((R)-pentan-2-yl)amino)ethyl)phenol -   (R)-1-(4-fluorophenyl)-2-(((R)-pentan-2-yl)amino)ethan-1-ol -   (R)-1-(3-fluorophenyl)-2-(((R)-pentan-2-yl)amino)ethan-1-ol

and pharmaceutically acceptable salts thereof.

The skilled person will understand that references to specific stereoisomer(s) of a compound of formula I will refer to the specific stereoisomer present in the substantial absence of the other corresponding stereoisomer(s).

The skilled person will also recognise that a compound of formula I may exist as a mixture of diastereomers (e.g. where the stereochemistry of the carbon substituted by the essential —OH group is an undefined configuration), or as a specific diastereomer (e.g. where the stereochemistry of carbon substituted by the essential —OH group is in a defined configuration). For example, particular diastereomers of compounds of formula I that may be mentioned (where the carbon substituted by the essential —OH group is in the (R) configuration) include the (R,R) diastereomer and the (R,S) disasteromer. These diastereomers may be referred to as being epimers of one another.

The skilled person will understand that references to a specific diastereomer of a compound of formula I (e.g. in the case of compounds of formula I, where the carbon substituted by the essential —OH group is in the (R) configuration, as represented by compounds of formula IB and formula IC) will refer to the specific diastereomer present in the substantial absence of other possible diastereomers (e.g. in the case of compounds of formula I, where the carbon substituted by the essential —OH group is in the (S) configuration).

For example, references to a compound of formula IC being present in the substantial absence of other diastereomers will refer to the substantial absence of the corresponding compounds as depicted below.

As used herein, references to the substantial absence of the corresponding opposite diastereomer will refer to the desired stereoisomer or mixture of stereoisomers (e.g. the desired diastereomer; such as in the case of compounds of formula I, where the carbon substituted by the essential —OH group is in the (R) configuration) being present at a purity of at least 80% (e.g. at least 90%, such as at least 95%) relative to other possible diastereomers (e.g. in the case of compounds of formula I, where the carbon substituted by the essential —OH group is in the (S) configuration and the carbon bearing the R¹ and R² groups is in either configuration, or where the carbon substituted by the essential —OH group is in the (R) configuration and the carbon bearing the R¹ and R² groups is in the (S) configuration). Alternatively, in such instances, compounds may be indicated to be present in the substantial absence of the compound in the other configurations, which may indicate that the compound in the relevant configuration is present in a diastereomeric excess (d.e.; i.e. an excess of the diastereoisomer or mixtures of diastereoisomers represented) of at least 90% (such as at least 95%, at least 98% or, particularly, at least 99%, for example at least 99.9%).

For the avoidance of doubt, compounds referred to as having a specific stereochemistry at a defined position (e.g. in the case of compounds of formula I, the carbon substituted by the essential —OH group being in the (R) configuration) may also have stereochemistry at one or more other positions, and so may exist as further mixtures of enantiomers or diastereomers in relation to the stereochemistry at those positions.

Medical Uses

As indicated herein, the compounds of the invention, and therefore compositions and kits comprising the same, are useful as pharmaceuticals.

Thus, according to a second aspect of the invention there is provided a compound of the first aspect of the invention, as hereinbefore defined (i.e. a compound as defined in the first aspect of the invention, including all embodiments and particular features thereof), for use as a pharmaceutical (or for use in medicine).

For the avoidance of doubt, references to compounds as defined in the first aspect of the invention will include references to compounds of formula I (including all embodiments thereof) and pharmaceutically acceptable salts thereof.

As indicated herein, the compounds of the invention may be of particular use in treating hyperglycaemia or a disorder characterized by hyperglycaemia.

Thus, in a third aspect of the invention, there is provided a compound of the first aspect of the invention, as hereinbefore defined, for use in the treatment of hyperglycaemia or a disorder characterized by hyperglycaemia.

In an alternative third aspect of the invention, there is provided the use of a compound of formula I, or a pharmaceutically acceptable salt thereof, in the manufacture of a medicament for use in the treatment of hyperglycaemia or a disorder characterized by hyperglycaemia.

In a further alternative third aspect of the invention, there is provided a method of treating hyperglycaemia or a disorder characterized by hyperglycaemia comprising administering to a patient in need thereof a therapeutically effective amount of a compound of formula I, or a pharmaceutically acceptable salt thereof.

For the avoidance of doubt, the term “hyperglycaemia” as used herein will be understood by those skilled in the art to refer to a condition wherein an excessive amount of glucose circulates in blood plasma of the subject experiencing the same. In particular, it may refer to a subject (e.g a human subject) having blood glucose levels higher than about 10.0 mmol/L (such as higher than about 11.1 mmol/L, e.g. higher than about 15 mmol/L), although it may also refer to a subject (e.g a human subject) having blood glucose levels higher than about 7 mmol/L for an extended period of time (e.g. for greater than 24 hours, such as for greater than 48 hours).

The skilled person will understand that references to the treatment of a particular condition (or, similarly, to treating that condition) take their normal meanings in the field of medicine. In particular, the terms may refer to achieving a reduction in the severity of one or more clinical symptom associated with the condition. For example, in the case of type 2 diabetes, the term may refer to achieving a reduction of blood glucose levels. In particular embodiments, in the case of treating hyperglycaemia or conditions characterised by hyperglycaemia, the term may refer to achieving a reduction of blood glucose levels (for example, to or below about 10.0 mmol/mL (e.g. to levels in the range of from about 4.0 mmol/L to about 10.0 mmol/L), such as to or below about 7.5 mmol/mL (e.g. to levels in the range of from about 4.0 mmol/L to about 7.5 mmol/L) or to or below about 6 mmol/mL (e.g. to levels in the range of from about 4.0 mmol/L to about 6.0 mmol/L)).

As used herein, references to patients will refer to a living subject being treated, including mammalian (e.g. human) patients. Thus, in particular embodiments of the first aspect of the invention, the treatment is in a mammal (e.g. a human).

As used herein, the term therapeutically effective amount will refer to an amount of a compound that confers a therapeutic effect on the treated patient. The effect may be objective (i.e. measurable by some test or marker) or subjective (i.e. the subject gives an indication of and/or feels an effect).

Although compounds of the first aspect of the invention may possess pharmacological activity as such, certain pharmaceutically-acceptable (e.g. “protected”) derivatives of compounds of the invention may exist or be prepared which may not possess such activity, but may be administered parenterally or orally and thereafter be metabolised in the body to form compounds of the invention. Such compounds (which may possess some pharmacological activity, provided that such activity is appreciably lower than that of the active compounds to which they are metabolised) may therefore be described as “prodrugs” of compounds of the invention.

As used herein, references to prodrugs will include compounds that form a compound of the invention, in an experimentally-detectable amount, within a predetermined time, following enteral or parenteral administration (e.g. oral or parenteral administration). All prodrugs of the compounds of the first aspect of the invention are included within the scope of the invention.

For the avoidance of doubt, the compounds of the first aspect of the invention are useful because they possess pharmacological activity, and/or are metabolised in the body following oral or parenteral administration to form compounds that possess pharmacological activity. In particular, as described herein, compounds of the first aspect of the invention are useful in the treatment of hyperglycaemia or disorders characterized by hyperglycaemia (such as type 2 diabetes), which terms will be readily understood by one of skill in the art (as described herein).

In a particular embodiment, the treatment is of a disorder (which may also be referred to as a condition or disease) characterised by hyperglycaemia.

In particular embodiments, compounds of the invention (i.e. compounds of formula I, including all embodiments thereof) are for use in the treatment of type 2 diabetes (or useful in the manufacture of a medicament for such treatment, or useful in a method for such treatment, as described herein).

In particular embodiments of the first aspect of the invention, the disorder is type 2 diabetes, such as type 2 diabetes of a sub-type selected from the list consisting of maturity-onset diabetes in the young (MODY), ketosis-prone diabetes in adults, latent autoimmune diabetes of adults (LADA), and gestational diabetes.

In further particular embodiments, the treatment of type 2 diabetes is in a non-obese patient.

For the avoidance of doubt, the skilled person will understand that patients with a Body Mass Index (BMI) of greater than 30 are considered to be obese.

In particular embodiments, the treatment may be of hyperglycaemia in a patient who is at risk of developing type 2 diabetes, which condition may be defined as pre-diabetes. Thus, compounds of the invention may be useful in the prevention of type 2 diabetes (e.g. in a patient having pre-diabetes).

As used herein, the term prevention (and, similarly, preventing) includes references to the prophylaxis of the disease or disorder (and vice-versa). As such, references to prevention may also be references to prophylaxis, and vice versa. In particular, the term may refer to achieving a reduction in the likelihood of the patient (or healthy subject) developing the condition (for example, at least a 10% reduction, such as at least a 20%, 30% or 40% reduction, e.g. at least a 50% reduction).

In more particular embodiments, the type 2 diabetes is characterised by the patient displaying severe insulin resistance (SIR).

In further embodiments, the treatment may be of hyperglycaemia in a patient having type 1 diabetes. Thus, compounds of the invention may be useful in the treatment of hyperglycaemia in type 1 diabetes.

The skilled person will understand that compounds of the invention may be useful in treating hyperglycaemia in patients having impaired insulin production, such as in patients having cystic fibrosis. Thus, in further embodiments, the disorder characterized by hyperglycaemia is cystic fibrosis-related diabetes.

In particular embodiments that may be mentioned, the disorder characterised by hyperglycaemia is (or is characterized by) severe insulin resistance (SIR), which may be understood by those in the art to refer to disorders wherein typically the subject has normal, or in some cases increased, insulin production but significantly reduced insulin sensitivity.

In particular instances, such patients may be non-obese (e.g. being of a healthy weight). Thus, in particular embodiments, such treatments are performed in patients who are not defined as being obese (e.g. in patients who are defined as being of a healthy weight).

For example, SIR may be identified in a patient based in said patient having fasting insulin >150 pmol/L and/or a peak insulin on glucose tolerance testing of >1,500 pmol/L, particularly in individuals with a BMI <30 kg/m² (which patient may otherwise have normal glucose tolerance).

More particularly, SIR may be characterised by the patient having no significant response to the presence of insulin, which may result from a defect (e.g. a genetic defect) in the function of the insulin receptor.

Particular disorders that may be characterised by SIR include: Rabson-Mendenhall syndrome, Donohue's syndrome (leprechaunism), Type A and Type B syndromes of insulin resistance, the HAIR-AN (hyperandrogenism, insulin resistance, and acanthosis nigricans) syndromes, pseudoacromegaly, and lipodystrophy.

More particular disorders that may be characterised by SIR include Donohue's syndrome and Type A syndrome of insulin resistance and, yet more particularly, Rabson-Mendenhall syndrome.

The skilled person will understand that treatment with compounds of the first aspect of the invention may further comprise (i.e. be combined with) further (i.e. additional/other) treatment(s) for the same condition. In particular, treatment with compounds of the invention may be combined with other means for the treatment of type 2 diabetes, such as treatment with one or more other therapeutic agent that is useful in the treatment of type 2 diabetes as known to those skilled in the art, such as therapies comprising requiring the patient to undergo a change of diet and/or undertake exercise regiments, and/or surgical procedures designed to promote weight loss (such as gastric band surgery).

In particular, treatment with compounds of the invention may be performed in combination with (e.g. in a patient who is also being treated with) one or more (e.g. one) additional compounds (i.e. therapeutic agents) that:

(i) are capable of reducing blood sugar levels; and/or

(ii) are insulin sensitizers; and/or

(iii) enhance insulin release,

all of which are described herein below.

In alternative embodiments, compounds of the first aspect of the invention (i.e. compounds of the invention) may be useful in the treatment of a non-alcoholic fatty liver disease (NAFLD).

Non-alcoholic fatty liver disease (NAFLD) is defined by excessive fat accumulation in the form of triglycerides (steatosis) in the liver (designated as an accumulation of greater than 5% of hepatocytes histologically). It is the most common liver disorder in developed countries (for example, affecting around 30% of US adults) and most patients are asymptomatic. If left untreated, the condition may progressively worsen and may ultimately lead to cirrhosis of the liver. NAFLD is particularly prevalent in obese patients, with around 80% thought to have the disease.

A sub-group of NAFLD patients (for example, between 2 and 5% of US adults) exhibit liver cell injury and inflammation in addition to excessive fat accumulation. This condition, designated as non-alcoholic steatohepatitis (NASH), is virtually indistinguishable histologically from alcoholic steatohepatitis. While the simple steatosis seen in NAFLD does not directly correlate with increased short-term morbidity or mortality, progression of this condition to NASH dramatically increases the risks of cirrhosis, liver failure and hepatocellular carcinoma. Indeed, NASH is now considered to be one of the main causes of cirrhosis (including cryptogenic cirrhosis) in the developed world.

The exact cause of NASH has yet to be elucidated, and it is almost certainly not the same in every patient. It is most closely related to insulin resistance, obesity, and the metabolic syndrome (which includes diseases related to diabetes mellitus type 2, insulin resistance, central (truncal) obesity, hyperlipidaemia, low high-density lipoprotein (HDL) cholesterol, hypertriglyceridemia, and hypertension). However, not all patients with these conditions have NASH, and not all patients with NASH suffer from one of these conditions. Nevertheless, given that NASH is a potentially fatal condition, leading to cirrhosis, liver failure and hepatocellular carcinoma, there exists a clear need for an effective treatment.

In particular embodiments, compounds of the invention (i.e. compounds of formula I, including all embodiments thereof) are for use in the treatment of a non-alcoholic fatty liver disease (or useful in the manufacture of a medicament for such treatment, or useful in a method for such treatment, as described herein).

The process by which the triglyceride fat accumulates in liver cells is called steatosis (i.e. hepatic steatosis). The skilled person will understand that the term “steatosis” encompasses the abnormal retention of fat (i.e. lipids) within a cell. Thus, in particular embodiments of the first aspect of the invention, the treatment or prevention is of a fatty liver disease which is characterized by steatosis.

During steatosis, excess lipids accumulate in vesicles that displace the cytoplasm of the cell. Over time, the vesicles can grow large enough to distort the nucleus, and the condition is known as macrovesicular steatosis. Otherwise, the condition may be referred to as microvesicular steatosis. Steatosis is largely harmless in mild cases; however, large accumulations of fat in the liver can cause significant health issues. Risk factors associated with steatosis include diabetes mellitus, protein malnutrition, hypertension, obesity, anoxia, sleep apnea and the presence of toxins within the cell.

As described herein, fatty liver disease is most commonly associated with alcohol or a metabolic syndrome (for example, diabetes, hypertension, obesity or dyslipidemia). Therefore, depending on the underlying cause, fatty liver disease may be diagnosed as alcohol-related fatty liver disease or non-alcoholic fatty liver disease (NAFLD).

Particular diseases or conditions that are associated with fatty liver disease that are not related to alcohol include metabolic conditions such as diabetes, hypertension, obesity, dyslipidemia, abetalipoproteinemia, glycogen storage diseases, Weber-Christian disease, acute fatty liver of pregnancy, and lipodystrophy. Other non-alcohol related factors related to fatty liver diseases include malnutrition, total parenteral nutrition, severe weight loss, refeeding syndrome, jejunoileal bypass, gastric bypass, polycystic ovary syndrome and diverticulosis.

The compounds of the invention have been found to be particularly useful in the treatment or prevention of NAFLD, which may be referred to as a fatty liver disease which is not alcohol related. A fatty liver disease which is “not alcohol related” may be diagnosed wherein alcohol consumption of the patient is not considered to be a main causative factor. A typical threshold for diagnosing a fatty liver disease as “not alcohol related” is a daily consumption of less than 20 g for female subjects and less than 30 g for male subjects.

If left untreated, subjects suffering from fatty liver disease may begin to experience inflammation of the the liver (hepatitis). It has been postulated that one of the possible causes of this inflammation may be lipid peroxidative damage to the membranes of the liver cells. Inflammation of a fatty liver can lead to a number of serious conditions and it is therefore desirable to treat or prevent fatty liver disease before inflammation occurs. Thus, in particular embodiments of the first aspect of the invention, the treatment or prevention is of a NAFLD which is associated with inflammation.

Non-alcoholic steatohepatitis (NASH) is the most aggressive form of NAFLD, and is a condition in which excessive fat accumulation (steatosis) is accompanied by inflammation of the liver. If advanced, NASH can lead to the development of scar tissue in the liver (fibrosis) and, eventually, cirrhosis. As described above, the compounds of the invention have been found to be useful in the treatment or prevention of NAFLD, particularly when accompanied by inflammation of the liver. It follows that the compounds of the invention are also useful in the treatment or prevention of NASH. Therefore, in a further embodiment of the first aspect of the invention, the treatment or prevention is of non-alcoholic steatohepatitis (NASH).

The skilled person will understand that treatment with compounds of the first aspect of the invention may further comprise (i.e. be combined with) further (i.e. additional/other) treatment(s) for the same condition. In particular, treatment with compounds of the invention may be combined with other means for the treatment of a fatty liver disease, as described herein, such as treatment with one or more other therapeutic agent that is useful in the treatment of a fatty liver disease as known to those skilled in the art; for example, therapies comprising requiring the patient to undergo a change of diet and/or undertake exercise regiments, and/or surgical procedures designed to promote weight loss (such as gastric band surgery).

In particular, treatment with compounds of the invention may be performed in combination with (e.g. in a patient who is also being treated with) one or more (e.g. one) additional compounds (i.e. therapeutic agents) that are capable of reducing the level of fat (e.g. triglycerides) in the liver.

References to treatment of a fatty liver disease may refer to achieving a therapeutically significant reduction of fat (e.g. triglycerides levels) in liver cells (such as a reduction of at least 5% by weight, e.g. a reduction of at least 10%, or at least 20% or even 25%).

Pharmaceutical Compositions

As described herein, compounds of the first aspect of the invention are useful as pharmaceuticals. Such compounds may be administered alone or may be administered by way of known pharmaceutical compositions/formulations.

In a fourth aspect of the invention, there is provided a pharmaceutical composition comprising a compound as defined in the first aspect of the invention (i.e. a compound of the invention), and optionally one or more pharmaceutically acceptable adjuvant, diluent and/or carrier.

The skilled person will understand that references herein to compounds of the first aspect of the invention being for particular uses (and, similarly, to uses and methods of use relating to compounds of the invention) may also apply to pharmaceutical compositions comprising compounds of the invention as described herein.

In a fifth aspect of the invention, there is provided a pharmaceutical composition for use in the treatment of hyperglycaemia or a disorder characterized by hyperglycaemia (as defined herein, such as type 2 diabetes) comprising a compound as defined in the first aspect of the invention, and optionally one or more pharmaceutically acceptable adjuvant, diluent and/or carrier.

In an alternative fifth aspect of the invention, there is provided a pharmaceutical composition for use in the treatment or prevention of a non-alcoholic fatty liver disease, as defined herein.

The skilled person will understand that compounds of the first aspect of the invention may act systemically and/or locally (i.e. at a particular site).

The skilled person will understand that compounds and compositions as described in the first to fifth aspects of the invention will normally be administered orally, intravenously, subcutaneously, buccally, rectally, dermally, nasally, tracheally, bronchially, sublingually, intranasally, topically, by any other parenteral route or via inhalation, in a pharmaceutically acceptable dosage form. Pharmaceutical compositions as described herein will include compositions in the form of tablets, capsules or elixirs for oral administration, suppositories for rectal administration, sterile solutions or suspensions for parenteral or intramuscular administration, and the like. Alternatively, particularly where such compounds of the invention act locally, pharmaceutical compositions may be formulated for topical administration.

Thus, in particular embodiments of the fourth and fifth aspects of the invention, the pharmaceutical formulation is provided in a pharmaceutically acceptable dosage form, including tablets or capsules, liquid forms to be taken orally or by injection, suppositories, creams, gels, foams, inhalants (e.g. to be applied intranasally), or forms suitable for topical administration. For the avoidance of doubt, in such embodiments, compounds of the invention may be present as a solid (e.g. a solid dispersion), liquid (e.g. in solution) or in other forms, such as in the form of micelles.

For example, in the preparation of pharmaceutical formulations for oral administration, the compound may be mixed with solid, powdered ingredients such as lactose, saccharose, sorbitol, mannitol, starch, amylopectin, cellulose derivatives, gelatin, or another suitable ingredient, as well as with disintegrating agents and lubricating agents such as magnesium stearate, calcium stearate, sodium stearyl fumarate and polyethylene glycol waxes. The mixture may then be processed into granules or compressed into tablets.

Soft gelatin capsules may be prepared with capsules containing one or more active compounds (e.g. compounds of the first and, therefore, second and third aspects of the invention, and optionally additional therapeutic agents), together with, for example, vegetable oil, fat, or other suitable vehicle for soft gelatin capsules. Similarly, hard gelatine capsules may contain such compound(s) in combination with solid powdered ingredients such as lactose, saccharose, sorbitol, mannitol, potato starch, corn starch, amylopectin, cellulose derivatives or gelatin.

Dosage units for rectal administration may be prepared (i) in the form of suppositories which contain the compound(s) mixed with a neutral fat base; (ii) in the form of a gelatin rectal capsule which contains the active substance in a mixture with a vegetable oil, paraffin oil, or other suitable vehicle for gelatin rectal capsules; (iii) in the form of a ready-made micro enema; or (iv) in the form of a dry micro enema formulation to be reconstituted in a suitable solvent just prior to administration.

Liquid preparations for oral administration may be prepared in the form of syrups or suspensions, e.g. solutions or suspensions, containing the compound(s) and the remainder of the formulation consisting of sugar or sugar alcohols, and a mixture of ethanol, water, glycerol, propylene glycol and polyethylene glycol. If desired, such liquid preparations may contain colouring agents, flavouring agents, saccharine and carboxymethyl cellulose or other thickening agent. Liquid preparations for oral administration may also be prepared in the form of a dry powder to be reconstituted with a suitable solvent prior to use.

Solutions for parenteral administration may be prepared as a solution of the compound(s) in a pharmaceutically acceptable solvent. These solutions may also contain stabilizing ingredients and/or buffering ingredients and are dispensed into unit doses in the form of ampoules or vials. Solutions for parenteral administration may also be prepared as a dry preparation to be reconstituted with a suitable solvent extemporaneously before use.

The skilled person will understand that compounds of the invention, and pharmaceutically-acceptable salts thereof, may be administered (for example, as formulations as described hereinabove) at varying doses, with suitable doses being readily determined by one of skill in the art. Oral, pulmonary and topical dosages (and subcutaneous dosages, although these dosages may be relatively lower) may range from between about 0.01 μg/kg of body weight per day (μg/kg/day) to about 200 μg/kg/day, preferably about 0.01 to about 10 μg/kg/day, and more preferably about 0.1 to about 5.0 μg/kg/day. For example, when administered orally, treatment with such compounds may comprise administration of a formulations typically containing between about 0.01 μg to about 2000 mg, for example between about 0.1 μg to about 500 mg, or between 1 μg to about 100 mg (e.g. about 20 μg to about 80 mg), of the active ingredient(s). When administered intravenously, the most preferred doses will range from about 0.001 to about 10 μg/kg/hour during constant rate infusion. Advantageously, treatment may comprise administration of such compounds and compositions in a single daily dose, or the total daily dosage may be administered in divided doses of two, three or four times daily (e.g. twice daily with reference to the doses described herein, such as a dose of 10 mg, 20 mg, 30 mg or 40 mg twice daily, or 10 μg, 20 μg, 30 μg or 40 μg twice daily).

In any event, the skilled person (e.g. the physician) will be able to determine the actual dosage which will be most suitable for an individual patient, which is likely to vary with the route of administration, the type and severity of the condition that is to be treated, as well as the species, age, weight, sex, renal function, hepatic function and response of the particular patient to be treated. The above-mentioned dosages are exemplary of the average case; there can, of course, be individual instances where higher or lower dosage ranges are merited, and such are within the scope of this invention.

As described herein above, the skilled person will understand that treatment with compounds of the first aspect of the invention may further comprise (i.e. be combined with) further (i.e. additional/other) treatment(s) for the same condition. In particular, treatment with compounds of the invention may be combined with other means for the treatment of hyperglycaemia or a disorder characterized by hyperglycaemia (as defined herein, such as type 2 diabetes), such as treatment with one or more other therapeutic agent that is useful in the treatment of hyperglycaemia or a disorder characterized by hyperglycaemia (as defined herein, such as type 2 diabetes).

In particular embodiments of the fourth and fifth aspects of the invention, the pharmaceutical composition may further comprise one or more additional (i.e. other) therapeutic agent.

In more particular embodiments, the one or more additional therapeutic agent is an agent for the treatment of type 2 diabetes as known to those skilled in the art, such as metformin, sulfonylureas (e.g. carbutamide, acetohexamide, chlorpropamide, tolbutamide. glipizide (glucotrol), gliclazide, glibenclamide, glyburide (Micronase), glibornuride, gliquidone, glisoxepide, glyclopyramide, glimepiride (Amaryl), glimiprime, JB253 or JB558), thiazolidinediones (e.g. pioglitazone, rosiglitazone (Avandia), lobeglitazone (Duvie) and troglitazone (Rezulin)), dipeptidyl peptidase-4 inhibitors (e.g. sitagliptin, vildagliptin, saxagliptin, linagliptin, anagliptin, teneligliptin, alogliptin, trelagliptin, gemigliptin, dutogliptin and omarigliptin), SGLT2 inhibitors (e.g. dapagliflozin, empagliflozin, canagliflozin, ipragliflozin, tofogliflozin, sergliflozin etabonate, remogliflozin etabonate, and ertugliflozin), and glucagon-like peptide-1 (GLP-1) analogues.

The skilled person will understand that combinations of therapeutic agents may also described as a combination product and/or provided as a kit-of-parts.

In a sixth aspect of the invention, there is provided a combination product comprising:

(A) a compound as defined in the first aspect of the invention; and

(B) one or more additional therapeutic agent,

wherein each of components (A) and (B) is formulated in admixture, optionally with one or more a pharmaceutically-acceptable adjuvant, diluent or carrier.

In a seventh aspect of the invention, there is provided a kit-of-parts comprising:

(a) a compound as defined in the first (or second and/or third) aspect of the invention, (or a pharmaceutical composition comprising the same) or a pharmaceutical composition as defined in the fourth or fifth aspect of the invention; and

(b) one or more other therapeutic agent, optionally in admixture with one or more pharmaceutically-acceptable adjuvant, diluent or carrier,

which components (a) and (b) are each provided in a form that is suitable for administration in conjunction with the other.

In particular embodiments (e.g. of the sixth and seventh aspects of the invention), the additional therapeutic agent is a therapeutic agent that is useful for the treatment of hyperglycaemia or a disorder characterized by hyperglycaemia (e.g. type 2 diabetes), as known to those skilled in the art (such as those described herein).

For example, in particular embodiments of the fourth to seventh aspects of the invention, the additional therapeutic agent is an agent that:

(i) is capable of reducing blood sugar levels; and/or

(ii) is an insulin sensitizer; and/or

(iii) is able to enhance insulin release,

which agents will be readily identified by those skilled in the art and include, in particular, such therapeutic agents that are commercially available (e.g. agents that the subject of a marketing authorization in one or more territory, such as a European or US marketing authorization).

The skilled person will understand that references to therapeutic agents capable of reducing blood glucose levels may refer to compounds capable of reducing levels of blood by at least 10% (such as at least 20%, at least 30% or at least 40%, for example at least 50%, at least 60%, at least 70% or at least 80%, e.g. at least 90%) when compared to the blood glucose levels prior to treatment with the relevant compound.

In alternative embodiments of the sixth and seventh aspects of the invention, the additional therapeutic agent is an agent for the treatment or prevention of a non-alcoholic fatty liver disease (such as NASH), which agents will be readily identified by those skilled in the art and include, in particular, such therapeutic agents that are commercially available (e.g. agents that the subject of a marketing authorization in one or more territory, such as a European or US marketing authorization).

Preparation of Compounds/Compositions

Pharmaceutical compositions/formulations, combination products and kits as described herein may be prepared in accordance with standard and/or accepted pharmaceutical practice.

Thus, in a further aspect of the invention there is provided a process for the preparation of a pharmaceutical composition/formulation, as hereinbefore defined, which process comprises bringing into association a compound of the invention, as hereinbefore defined, with one or more pharmaceutically-acceptable adjuvant, diluent or carrier.

In further aspects of the invention, there is provided a process for the preparation of a combination product or kit-of-parts as hereinbefore defined, which process comprises bringing into association a compound of the invention, as hereinbefore defined, or a pharmaceutically acceptable salt thereof with the other therapeutic agent that is useful in the treatment of hyperglycaemia or a disorder characterized by hyperglycaemia (e.g. type 2 diabetes), and at least one pharmaceutically-acceptable adjuvant, diluent or carrier.

As used herein, references to bringing into association will mean that the two components are rendered suitable for administration in conjunction with each other.

Thus, in relation to the process for the preparation of a kit of parts as hereinbefore defined, by bringing the two components “into association with” each other, we include that the two components of the kit of parts may be:

(i) provided as separate formulations (i.e. independently of one another), which are subsequently brought together for use in conjunction with each other in combination therapy; or

(ii) packaged and presented together as separate components of a “combination pack” for use in conjunction with each other in combination therapy.

Compounds as defined in the first aspect of the invention (i.e. compounds of the invention) may be prepared in accordance with techniques that are well known to those skilled in the art, such as those described in the examples provided hereinafter.

For example, there is provided a process for the preparation of a compound of formula I, or a pharmaceutically acceptable salt thereof, as defined in the first aspect of the invention (which may be utilised in the preparation of, for example, a compound as defined in the second aspect of the invention), which process comprises:

(i) reaction of a compound of formula II

wherein n, X, R³, R⁴ and n are as defined hereinabove, with a compound of formula III

wherein R¹ and R² are as defined hereinabove, optionally in the presence of a suitable solvent known to those skilled in the art;

(iia) reaction of a compound of formula IV

wherein n, X, R¹, R², R³ and R⁴ are as defined hereinabove and Y¹ represents H or PG¹ wherein PG¹ is a suitable protecting group as known to those skilled in the art (e.g. —C(O)OtBu or —SO₂CH₃) with a suitable reduction agent as known to those skilled in the art, such as NaBH₄ or LiAlH₄, or by hydrogenation in the presence of a suitable catalyst;

(iib) for compounds of formula IB (and, similarly, compounds of formula IC) reaction of a compound of formula IV as defined herein above but wherein Y¹ represents PG¹ wherein PG¹ is a suitable protecting group as known to those skilled in the art (e.g. —C(O)OtBu) in the presence of a suitable catalyst (such as a complex between (1S,2S)-(+)-N-(4-toluenesulphonyl)-1,2-diphenylethylene diamine and [Ru(cymene)Cl₂]₂)) in the presence of hydrogen or a suitable hydrogen donor (such as formic acid) and optionally in the presence of a base (e.g. Et₃N) and in the presence of a suitable solvent (such as CH₂Cl₂);

(iii) for compounds wherein at least one X is present and represents —OH, deprotection of a compound of formula V

wherein n, R¹, R², R³ and R⁴ and * are as defined hereinabove, Y² represents H or PG², wherein PG² represents a suitable protecting group as known to those skilled in the art, and PG³ represents a suitable protecting group as known to those skilled in the art (e.g. benzyl or alkyl, such as methyl) under conditions known to those skilled in the art (for example, in the case of benzyl, in the presence of hydrogen and a suitable catalyst or a suitable acid; in the case of alkyl, such as methyl, in the presence of BBr₃, HBr or alkyl sulfides);

(iv) for compounds wherein at least one X is present and represents NH₂, deprotection of a compound of formula VI

wherein n, X, R¹, R², R³ and R⁴ are as defined hereinabove, Y³ represents H or PG⁵, wherein PG⁵ represents a suitable protecting group as known to those skilled in the art, Y⁴ represents H or PG⁶, wherein PG⁶ represents a suitable protecting group as known to those skilled in the art, and PG⁴ represents a suitable protecting group as known to those skilled in the art (e.g. carbamate protecting groups (such as tert-butyloxycarbonyl (Boc), fluorenylmethyloxycarbonyl (Fmoc) and carboxybenzyl (Cbz) and amide protecting groups (such as acetyl and benzoyl)) under conditions known to those skilled in the art (for example in the case of Boc, in the presence of a suitable acid (e.g. trifluoroacetic acid or HCl). PG⁴, PG⁵ (if present) and PG⁶ (if present) may each represent the same protecting group, and therefore may be deprotected under a single set of conditions;

(v) for compounds wherein at least one X is present and represents NH₂, reduction of a compound of formula VII

wherein n, X, R¹, R², R³, R⁴ and * are as defined hereinabove, under conditions known to those skilled in the art (for example, by hydrogenation, such as hydrogenation using hydrogen gas and a suitable catalyst as known to those skilled in the art, (e.g. Pd—C, PtO₂, Raney-Nickel), Fe or Zn in acidic media (e.g. AcOH), borohydrides together with a suitable catalyst (e.g. NaBH₄ and Raney-Nickel), or agents such as SnCl₂, TiCl₃, SmI₂, and the like.

Those skilled in the art will understand that certain functional groups, such as the essential —OH and/or the —NHR¹ groups) may need to be protected (and deprotected) one or more times during the reaction, which protections (and deprotections) may be performed using techniques known to those skilled in the art.

Compounds of formulae II, III, IV, V, VI and VII are either commercially available, are known in the literature, or may be obtained either by analogy with the processes described herein, or by conventional synthetic procedures, in accordance with standard techniques, from available starting materials (e.g. appropriately substituted benzaldehydes, styrenes or phenacyl bromides (or phenacylchloride, and the like) using appropriate reagents and reaction conditions. In this respect, the skilled person may refer to inter alia “Comprehensive Organic Synthesis” by B. M. Trost and I. Fleming, Pergamon Press, 1991. Further references that may be employed include “Science of Synthesis”, Volumes 9-17 (Hetarenes and Related Ring Systems), Georg Thieme Verlag, 2006.

The substituents X, R¹, R², R³ and R⁴, as hereinbefore defined, may be modified one or more times, after or during the processes described above for preparation of compounds of formula I by way of methods that are well known to those skilled in the art. Examples of such methods include substitutions, reductions, oxidations, dehydrogenations, alkylations, dealkylations, acylations, hydrolyses, esterifications, etherifications, halogenations and nitrations. The precursor groups can be changed to a different such group, or to the groups defined in formula I, at any time during the reaction sequence. The skilled person may also refer to “Comprehensive Organic Functional Group Transformations” by A. R. Katritzky, O. Meth-Cohn and C. W. Rees, Pergamon Press, 1995 and/or “Comprehensive Organic Transformations” by R. C. Larock, Wiley-VCH, 1999.

Such compounds may be isolated from their reaction mixtures and, if necessary, purified using conventional techniques as known to those skilled in the art. Thus, processes for preparation of compounds of the invention as described herein may include, as a final step, isolation and optionally purification of the compound of the invention (e.g. isolation and optionally purification of the compound of formula I or IA).

The skilled person will understand that compounds of formula I having additional specific stereochemistry (such as compounds of formula IB and IC) may be provided by reacting suitable starting materials having the required stereochemistry in processes as described herein.

For example, compounds of formula IB and IC may be provided by reacting compounds having the required stereochemistry in processes as described in step (i) or step (iii) in the processes described herein above.

Further, the skilled person will understand that suitable starting materials having the required stereochemistry (such as suitable compounds of formula II and V wherein the carbon substituted with the essential oxygen is the (R) configuration, as required for the preparation of compounds of formula IB and IC) may be prepared by analogy with the process described in step (iib) herein above.

It will be appreciated by those skilled in the art that, in the processes described above and hereinafter, the functional groups of intermediate compounds may need to be protected by protecting groups. The protection and deprotection of functional groups may take place before or after a reaction in the above-mentioned schemes.

Protecting groups may be applied and removed in accordance with techniques that are well known to those skilled in the art and as described hereinafter. For example, protected compounds/intermediates described herein may be converted chemically to unprotected compounds using standard deprotection techniques. The type of chemistry involved will dictate the need, and type, of protecting groups as well as the sequence for accomplishing the synthesis. The use of protecting groups is fully described in “Protective Groups in Organic Synthesis”, 3rd edition, T. W. Greene & P. G. M. Wutz, Wiley-Interscience (1999).

Compounds as described herein (in particular, compounds as defined in the first and, therefore, second and third aspects of the invention) may have the advantage that they may be more efficacious than, be less toxic than, be longer acting than, be more potent than, produce fewer side effects than, be more easily absorbed than, and/or have a better pharmacokinetic profile (e.g. higher oral bioavailability and/or lower clearance) than, and/or have other useful pharmacological, physical, or chemical properties over, compounds known in the prior art, whether for use in the above-stated indications or otherwise. In particular, such compounds may have the advantage that they are more efficacious and/or exhibit advantageous properties in vivo.

Without wishing to be bound by theory, compounds as described herein are thought to be potent agonists of the β₂-adrenergic receptor, which allows for increased glucose uptake in skeletal muscle cells.

In addition, compounds as described herein are thought to be agonists of the β₂-adrenergic receptor without (or with only a minimal effect in) inducing cAMP production. It is thought that this allows for the increased glucose uptake in skeletal muscle cells with lower levels of side effects than would result from other treatments. Further, combining compounds as described herein with therapeutic agents that are able to decrease blood glucose levels is thought to provide an effective combination therapy.

EXAMPLES

The present invention is illustrated by way of the following examples.

Chemicals and reagents were obtained from commercial suppliers and were used as received unless otherwise stated. All reactions involving moisture sensitive reagents were performed in oven or flame dried glassware under a positive pressure of nitrogen or argon.

Abbreviations

Abbreviations as used herein will be known to those skilled in the art. In particular, the following abbreviations may be used herein.

AcOH acetic acid

aq aqueous

Boc₂O di-tert-butyl dicarbonate

de diastereomeric excess

DIPEA N,N-diisopropylethylamine

EtOAc ethyl acetate

EtOH ethanol

Et₂O diethyl ether

Et₃N triethylamine

h hours

HPLC high-performance liquid chromatography

MeOH methanol

Pd—C palladium on carbon

rt room temperature

Example Compounds

In the event that there is a discrepancy between nomenclature and the structure of compounds as depicted graphically, it is the latter that presides (unless contradicted by any experimental details that may be given and/or unless it is clear from the context).

In the event that there is a discrepancy between nomenclature and the structure of compounds as depicted graphically, it is the latter that presides (unless contradicted by any experimental details that may be given and/or unless it is clear from the context).

Example 1: 4-((R)-1-Hydroxy-2-(((R)-pentan-2-yl)amino)ethyl)phenol Acetate

(a) 4-Benzyloxyacetophenone

K₂CO₃ (7.5 g, 54.4 mmol) was added to a solution of 4-hydroxyacetophenone (3.7 g, 27.2 mmol) in acetone (180 mL) at rt. The mixture was stirred at rt for 1 h and benzylbromide (3.2 mL, 27.2 mmol) was added. The mixture was heated at reflux for 12 h, allowed to cool and filtered. Concentration of the filtrate gave the sub-title compound (6.1 g, 27.1 mmol, ˜100%) which was used in the next step without further purification.

(b) 4-Benzyloxyphenacyl Bromide

Pyridinium tribromide (9.5 g, 29.8 mmol) was added to a solution of 4-benzyloxyacetophenone (6.1 g, 27.1 mmol) in CH₂Cl₂ (275 mL) and MeOH (100 mL) at rt. After 3 h at rt the mixture was concentrated and the residue partitioned between water and EtOAc. The layers were separated and the aqueous layer was extracted with EtOAc. The combined organic phases were washed with brine, dried over Na₂SO₄ and filtered. Concentration of the filtrate and crystallization of the residue from hexane/EtOAc gave the sub-title compound (6.4 g, 21.1 mmol, 78%).

(c) tert-Butyl (R)-(2-(4-(benzyloxy)phenyl)-2-oxoethyl)(pentan-2-yl)carbamate

DIPEA (1.9 mL, 10.8 mmol) was added dropwise to a solution of (R)-pentyl-2-amine hydrobromide (1.2 g, 7.21 mmol) in CH₂Cl₂ (70 mL) at −20° C. 4-Benzyloxyphenacyl bromide (1.1 g, 3.60 mmol) in CH₂Cl₂ (50 mL) was added over 15 min at −20° C. The mixture was stirred at −20° C. for 2 h and kept at that temperature for 60 h. Boc₂O (4.1 mL, 18.0 mmol) was added and the mixture was stirred at rt for 2 h. The mixture was washed with water and brine, dried over Na₂SO₄, concentrated and purified by chromatography to give the sub-title compound (0.60 g, 1.46 mmol, 40%).

(d) tert-Butyl ((R)-2-(4-(benzyloxy)phenyl)-2-hydroxyethyl)((R)-pentan-2-yl)carbamate

A mixture of tert-butyl (S)-(2-(4-(benzyloxy)phenyl)-2-oxoethyl)(pentan-2-yl)carbamate (300 mg, 0.73 mmol), (S,S)—N-(p-toluenesulfonyl)-1,2-diphenylethanediamine(chloro)-(p-cymene)ruthenium(II) (20 mg, 0.03 mmol) and formic acid/Et₃N (5:2, 2 mL) was stirred at rt for 24 h and additional portions of catalyst (20 mg) and formic acid/Et₃N (5:2, 0.25 mL) were added. This procedure was repeated at 24 h intervals five more times (total amount of catalyst 120 mg (0.30 mmol), total reaction time 7 d). Water (15 mL) and CH₂Cl₂ (30 mL) were added and the aq layer was extracted with CH₂Cl₂. The combined organic phases were washed with brine, dried over Na₂SO₄ and concentrated. The residue was purified by chromatography and HPLC to give the sub-title compound (0.25 g, 0.60 mmol, de>99%, 83%).

(e) (R)-1-(4-(Benzyloxy)phenyl)-2-(((R)-pentan-2-yl)amino)ethan-1-ol

A solution of NaOH (0.43 g, 10.6 mmol) in water (2 mL) was added to a solution of tert-butyl ((R)-2-(4-(benzyloxy)phenyl)-2-hydroxyethyl)((R)-pentan-2-yl)carbamate (0.22 g, 0.53 mmol) in EtOH (3 mL). The mixture was heated at 100° C. in a sealed tube for 40 h and allowed to cool. Water and EtOAc was added and the layers were separated. The aq layer was extracted with EtOAc and the combined organic phases were washed with brine, dried over Na₂SO₄ and concentrated to give the sub-title compound which was used in the next step without further purification (0.13 mg, 0.41 mmol, 78%).

(f) 4-((R)-1-Hydroxy-2-(((R)-pentan-2-yl)amino)ethyl)phenol Acetate

A mixture of (R)-1-(4-(benzyloxy)phenyl)-2-(((R)-pentan-2-yl)amino)ethan-1-ol (125 mg, 0.40 mmol), 10% Pd—C (85 mg, 0.08 mmol) and AcOH (3 mL) was hydrogenated at 9 atm at rt for 1.5 h, filtered through Celite and concentrated. The residue was taken up into a small amount of water, filtered through Celite and the filtrate was concentrated to about 1 mL. The material was purified by reverse phase chromatography to give the title compound (60 mg, 0.21 mmol, de>99%, 53%).

¹H NMR (400 MHz, D₂O) δ 7.38-7.30 (m, 2H), 6.98-6.92 (m, 2H), 4.96 (t, J=6.6 Hz, 1H), 3.43-3.33 (m, 1H), 3.29 (d, J=6.6 Hz, 2H), 1.92 (s, 3H), 1.78-1.67 (m, 1H), 1.64-1.52 (m, 1H), 1.51-1.34 (m, 2H), 1.32 (d, J=6.6 Hz, 3H), 0.93 (t, J=7.3 Hz, 3H).

Example 2: 4-((R)-1-Hydroxy-2-(((R)-pentan-2-yl)amino)ethyl)phenol Hemisulphate

Sulphuric acid (aq, 0.1 M, 0.85 mL) was added to a solution of the acetate in Example 1 (48 mg, 0.17 mmol) in H₂O (1 mL). The mixture was concentrated and dried over P₂O₅. The residue was treated with toluene (2 mL) and concentrated. The procedure was repeated and the residue was treated with Et₂O, concentrated and dried over P₂O₅ to give the title compound (34 mg, 0.12 mmol, 74%)

¹H NMR (400 MHz, D₂O) δ 7.37-7.31 (m, 2H), 6.98-6.92 (m, 2H), 4.96 (t, J=6.6 Hz, 1H), 3.45-3.34 (m, 1H), 3.29 (d, J=6.7 Hz, 2H), 1.79-1.68 (m, 1H), 1.65-1.53 (m, 1H), 1.52-1.34 (m, 2H), 1.33 (d, J=6.6 Hz, 3H), 0.93 (t, J=7.3 Hz, 3H).

Example 3: 3-((R)-1-Hydroxy-2-(((R)-pentan-2-yl)amino)ethyl)phenol Acetate

The title compound was prepared in accordance with Example 1, using 3-benzyloxyacetophenone in Step (b).

¹H NMR (400 MHz, D₂O) δ 7.37-7.32 (m, 1H), 7.01-6.96 (m, 1H), 6.95-6.88 (m, 2H), 4.98 (dd, J=9.1, 3.9 Hz, 1H), 3.42-3.34 (m, 1H), 3.31 (dd, J=13.0, 3.9 Hz, 1H), 3.26 (dd, J=13.0, 9.1 Hz, 1H), 1.91 (s, 3H), 1.77-1.67 (m, 1H), 1.64-1.52 (m, 1H), 1.51-1.33 (m, 2H), 1.32 (d, J=6.6 Hz, 3H), 0.93 (t, J=7.3 Hz, 3H).

Example 4: 3-((R)-1-Hydroxy-2-(((R)-pentan-2-yl)amino)ethyl)phenol Hemisulphate

The title compound was prepared in accordance with Example 3, using the acetate from Example 2.

¹H NMR (400 MHz, D₂O) δ 7.35 (t, J=7.9 Hz, 1H), 7.00 (d, J=7.7 Hz, 1H), 6.97-6.88 (m, 2H), 4.99 (dd, J=9.1, 3.7 Hz, 1H), 3.45-3.22 (m, 3H), 1.79-1.66 (m, 1H), 1.65-1.52 (m, 1H), 1.52-1.35 (m, 2H), 1.32 (d, J=6.6 Hz, 3H), 0.93 (t, J=7.3 Hz, 3H).

Example 5: (R)-1-(4-Fluorophenyl)-2-(((R)-pentan-2-yl)amino)ethan-1-ol

(a) tert-Butyl (2-(4-fluorophenyl)-2-oxoethyl)(pentan-2-yl)carbamate

A solution of 4-fluorophenacyl bromide (500 mg, 2.31 mmol) in CH₂Cl₂ (6.6 mL) was added over 10 min to a solution of 2-aminopentane (301 mg, 3.46 mmol) and DIPEA (298 mg, 2.31 mmol) in CH₂Cl₂ (1.6 mL) at 0° C. The cooling bath was removed and the mixture was stirred at rt for 2 h. A solution of Boc₂O (1.26 g, 5.76 mmol) in CH₂Cl₂ (6 mL) was added and the mixture was stirred at rt for 2 h, washed with H₂O, brine and dried over Na₂SO₄. Concentration and purification by chromatography gave the sub-title compound (520 mg, 1.61 mmol, 70%).

(b) (R)-1-(4-Fluorophenyl)-2-(((R)-pentan-2-yl)amino)ethan-1-ol

The title compound was obtained using the procedures in Example 1, Step (d) followed by chromatographic separation and hydrolysis in accordance with the procedure in Example 1, step (e).

¹H NMR (400 MHz, CDCl₃): δ 7.34 (dd, J=8.4, 5.6 Hz, 2H), 7.03 (t, J=8.4 Hz, 2H), 4.61 (dd, J=9.4, 3.4 Hz, 1H), 2.91 (dd, J=12.0, 3.6 Hz, 1H), 2.69-2.59 (m, 2H), 1.47-1.28 (m, 4H), 1.06 (d, J=6.0 Hz, 3H), 0.91 (t, J=6.8 Hz, 3H).

Example 6: (R)-1-(3-fluorophenyl)-2-(((R)-pentan-2-yl)amino)ethan-1-ol

The title compounds were prepared in accordance with Example 5 from 3-fluorophenacyl bromide.

¹H NMR (400 MHz, CDCl₃): δ 7.33-7.26 (m, 1H), 7.14-7.09 (m, 2H), 7.00-6.90 (m, 1H), 4.66 (dd, J=8.8, 3.6 Hz, 1H), 2.97-2.92 (m, 1H), 2.72-2.62 (m, 3H), 1.47-1.26 (m, 4H), 1.07 (dd, J=6.4, 1.2 Hz, 3H), 0.93-0.89 (m, 3H).

BIOLOGICAL EXAMPLES

L6-myoblasts were grown in Dulbecco's Modified Eagle's Medium (DMEM) containing 4.5 g/l glucose supplemented with 10% fetal bovine serum, 2 mM L-Glutamine, 50 U/ml penicillin, 50 μg/ml streptomycin and 10 mM HEPES. Cells were plated at 1×10⁵ cells per ml in 24-well plates. After reaching 90% confluence the cells were grown in medium containing 2% FBS for 7 days where upon cells differentiated into myotubes.

Biological Example 1: Glucose Uptake

Differentiated L6-myotubes were serum-starved over night in medium containing 0.5% fatty-acid free BSA and stimulated with agonist, final concentration 1×10⁻⁵. After 1 h 40 min cells were washed with warm, glucose free medium or PBS and another portion of agonist was added to glucose free medium. After 20 min the cells were exposed to 50 nM ³H-2-deoxy-glucose for another 10 min before washed in ice cold glucose free medium or PBS and lysed in 0.2 M NaOH for 1 h in 60° C. Cell lysate was mixed with scintillation buffer (Emulsifier Safe, Perkin Elmer and radioactivity detected in a β-counter (Tri-Carb 2800TR, Perkin Elmer). The activity for each compound is compared to that of isoproterenol. If a compound shows activity of more than 75% of that of isoproterenol, the activity is denoted with +++, if it is between 75 and 50% it is denoted with ++; if it is between 50 and 25% it is denoted with +; if it less than 25% it is denoted with −.

Biological Example 2: Measurement of Intracellular cAMP Levels

Differentiated cells were serum-starved over night and stimulated with agonist, final concentration 1×10⁻⁵, for 15 min in stimulation buffer (HBSS supplemented with 1% BSA, 5 mM HEPES and 1 mM IBMX, pH 7.4) The medium was then aspirated and to end the reaction 100 μL of 95% EtOH was added to each well of a 24-well plate and cells were kept in −20° C. over night. The EtOH was let to evaporate and 500 μL of lysis buffer (1% BSA, 5 mM HEPES and 0.3% Tween-20, pH 7.4) was added to each well before put in −80° C. for 30 min and then kept in −20° C. Intracellular cAMP levels were detected using an alpha screen cAMP kit (6760635D from Perkin Elmer). The activity for each compound is compared to that of isoproterenol. If a compound shows activity of more than 75% of that of isoproterenol, the activity is denoted with +++, if it is between 75 and 50% it is denoted with ++; if it is between 50 and 25% it is denoted with +; if it less than 25% it is denoted with −.

Using the assays described in Biological Examples 1 and 2 the following results were obtained.

Compound Biological Biological example no. example 1 example 2 2 ++ + 4 +++ ++ 5 ++ − 6 ++ − 

The invention claimed is:
 1. A compound of formula I

or a pharmaceutically acceptable salt thereof, wherein: R¹ represents C₃₋₁₁ alkyl, C₃₋₁₁ alkenyl, or C₃₋₁₁ alkynyl each optionally substituted by one or more halo; R² represents C₁₋₂ alkyl, C₂ alkenyl, or C₂ alkynyl each optionally substituted by one or more halo; R³ and R⁴ each independently represent H or C₁₋₃ alkyl, C₂₋₃ alkenyl, or C₂₋₃ alkynyl each optionally substituted by one or more halo; or R³ and R⁴ may be linked together to form, together with the carbon atom to which they are attached, a 3- to 6-membered ring, which ring optionally is substituted by one or more groups independently selected from halo and C₁ alkyl optionally substituted by one or more halo; each X independently represents halo, R^(a), —CN, —N₃, —N(R^(b))R^(c), —NO₂, —ONO₂, —OR^(d), —S(O)_(p)R^(e) or —S(O)_(q)N(R^(f))R^(g); R^(a) represents C₁₋₆ alkyl, C₂₋₆ alkenyl, or C₂₋₆ alkynyl each optionally substituted by one or more groups independently selected from G; each R^(b), R^(c), R^(d), R^(e), R^(f) and R^(g) independently represents H or C₁₋₆ alkyl, C₂₋₆ alkenyl, or C₂₋₆ alkynyl each optionally substituted by one or more groups independently selected from G; or alternatively any of R^(b) and R^(c) and/or R^(f) and R^(g) may be linked together to form, together with the nitrogen atom to which they are attached, a 4- to 6-membered ring, which ring optionally contains one further heteroatom and which ring optionally is substituted by one or more groups independently selected from halo, C₁₋₃ alkyl, C₂₋₃ alkenyl, and C₂₋₃ alkynyl each optionally substituted by one or more halo, and ═O; G represents halo, —CN, —N(R^(a1))R^(b1), OR^(c1), —S(O)_(p)R^(d1), —S(O)_(q)N(R^(e1))R^(f1) or ═O; each R^(a1), R^(b1), R^(c1), R^(d1), R^(e1) and R^(f1) independently represents H or C₁₋₆ alkyl, C₂₋₆ alkenyl, or C₂₋₆ alkynyl each optionally substituted by one or more halo; or alternatively any of R^(a1) and R^(b1) and/or R^(e1) and R^(f1) may be linked together to form, together with the nitrogen atom to which they are attached, a 4- to 6-membered ring, which ring optionally contains one further heteroatom and which ring optionally is substituted by one or more groups independently selected from halo, C₁₋₃ alkyl, C₂₋₃ alkenyl, and C₂₋₃ alkynyl each optionally substituted by one or more halo, and ═O; n represents 0 to 5; each p independently represents 0, 1 or 2; and each q independently represents 1 or 2; wherein the compound of formula I is present in a diastereomeric excess of at least 90%.
 2. The compound according to claim 1, wherein R¹ represents C₃₋₆ alkyl optionally substituted by one or more F.
 3. The compound according to claim 1, wherein R² represents C₁₋₂ alkyl optionally substituted by one or more F.
 4. The compound according to claim 1, wherein R¹ represents n-propyl and R² represents methyl.
 5. The compound according to claim 1, wherein R³ and R⁴ each represent H.
 6. The compound according to claim 1, wherein: each X independently represents halo, R^(a), —CN, —N₃, —N(R^(b))R^(c), —NO₂ or OR^(d), wherein R^(a) represents C₁₋₄ alkyl optionally substituted by one or more F, and wherein R^(b), R^(c) and R^(d) each independently represent H or C₁₋₄ alkyl optionally substituted by one or more F or ═O.
 7. The compound according to claim 1, wherein n represents 0, 1, 2 or
 3. 8. The compound according to claim 1, wherein the compound is a compound of formula IA

wherein: X¹, X², X³, X⁴ and X⁵ each independently represent H or X.
 9. The compound according to claim 8, wherein: X¹ and X⁵ each represent H; and X², X³ and X⁴ each independently represent H, halo, R^(a), —CN, —N₃, —N(R^(b))R^(c), —NO₂ or —OR^(d); wherein R^(a) represents C₁₋₄ alkyl optionally substituted by one or more F, and wherein R^(b), R^(c) and R^(d) each independently represent H or C₁₋₄ alkyl optionally substituted by one or more F or ═O.
 10. The compound according to claim 8, wherein the compound of formula I or formula IA is a compound of formula IC


11. The compound according to claim 10, wherein: X¹, X² and X⁵ each represent H; X³ and X⁴ each independently represent H, F or —OH; R¹ represents C₃ alkyl; R² represents C₁ alkyl; and R³ and R⁴ both represent H.
 12. A pharmaceutical composition comprising a compound as defined in claim 1, and optionally one or more pharmaceutically acceptable adjuvant, diluent and/or carrier.
 13. A method of treating hyperglycaemia or a disorder characterized by hyperglycaemia comprising administering to a patient in need thereof a therapeutically effective amount of a compound as defined in claim 1, or a pharmaceutically acceptable salt thereof.
 14. The method according to claim 13, wherein the hyperglycaemia or disorder characterized by hyperglycaemia is type 2 diabetes.
 15. The method according to claim 13, wherein the patient displays severe insulin resistance.
 16. The method according to claim 13, wherein the disorder characterised by hyperglycaemia is selected from the group consisting of Rabson-Mendenhall syndrome, Donohue's syndrome (leprechaunism), Type A and Type B syndromes of insulin resistance, the HAIR-AN (hyperandrogenism, insulin resistance, and acanthosis nigricans) syndromes, pseudoacromegaly, and lipodystrophy.
 17. A combination product comprising: (a) a compound as defined in claim 1; and (b) one or more other therapeutic agent that is useful in the treatment of hyperglycaemia or a disorder characterized by hyperglycaemia, wherein each of components (a) and (b) is formulated in admixture, optionally with one or more a pharmaceutically-acceptable adjuvant, diluent or carrier.
 18. A kit-of-parts comprising: (a) a pharmaceutical composition comprising a compound as defined in claim 1, and optionally one or more pharmaceutically acceptable adjuvant, diluent and/or carrier, and (b) one or more other therapeutic agent that is useful in the treatment of hyperglycaemia or a disorder characterized by hyperglycaemia, optionally in admixture with one or more pharmaceutically-acceptable adjuvant, diluent or carrier, which components (a) and (b) are each provided in a form that is suitable for administration in conjunction with the other.
 19. A process for the preparation of a compound as defined in claim 1, or a pharmaceutically acceptable salt thereof, comprising the step of: (i) reaction of a compound of formula II

wherein n, X, R³, R⁴ and n are as defined in claim 1, with a compound of formula III

wherein R¹ and R² are as defined in claim 1, optionally in the presence of a suitable solvent known to those skilled in the art; (iia) reaction of a compound of formula IV

wherein n, X, R¹, R², R³ and R⁴ are as defined in claim 1 and Y¹ represents H or PG¹ wherein PG¹ is a suitable protecting group as known to those skilled in the art with a suitable reduction agent as known to those skilled in the art; (iib) for compounds of formula IC

wherein X¹, X², X³, X⁴ and X⁵ each independently represent H or X, wherein X, R¹, R², R³, and R⁴ are as defined in claim 1, reaction of a compound of formula IV as defined in step (iia) but wherein Y¹ represents PG¹ wherein PG¹ is a suitable protecting group as known to those skilled in the art in the presence of hydrogen or a suitable hydrogen donor and optionally in the presence of a base and in the presence of a suitable solvent; (iii) for compounds wherein at least one X is present and represents —OH, deprotection of a compound of formula V

wherein n, R¹, R², R³ and R⁴ are as defined in claim 1, Y² represents H or PG², wherein PG² represents a suitable protecting group as known to those skilled in the art, and PG³ represents a suitable protecting group as known to those skilled in the art under conditions known to those skilled in the art; (iv) for compounds wherein at least one X is present and represents NH₂, deprotection of a compound of formula VI

wherein n, X, R¹, R², R³ and R⁴ are as defined in claim 1, Y³ represents H or PG⁵, wherein PG⁵ represents a suitable protecting group as known to those skilled in the art, Y⁴ represents H or PG⁶, wherein PG⁶ represents a suitable protecting group as known to those skilled in the art, and PG⁴ represents a suitable protecting group as known to those skilled in the art, under conditions known to those skilled in the art; (v) for compounds wherein at least one X is present and represents NH₂, reduction of a compound of formula VII

wherein n, X, R¹, R², R³ and R⁴ are as defined in claim 1, under conditions known to those skilled in the art. 